This invention relates to borescopes or endoscopes of the type in which a miniature video camera is mounted at a distal viewing head of an elongated insertion tube. The invention is more particularly concerned with an arrangement of the miniature video camera which produces left-eye and right-eye stereo images using a single video imaging device and a single lens assembly.
Recently, interest has increased in the use of video instruments for surgical applications to permit a surgeon to carry out a procedure with minimal intervention in the patient. An example of one such video instrument is a laparoscope for performing surgery in the abdominal cavity, where the instrument is inserted through a small incision. Unfortunately, a video laparoscope or other optical laparoscope provides only a two-dimensional view of the area where surgery is to be performed. Consequently, there is an interest in stereo laparoscopy to aid the surgeon in identifying and repairing or removing tissues in question. There is also an increased interest in remote imaging of industrial process, such an inspection of heat exchanger tubes or of turbine engines, where stereoscopic imaging could be employed to advantage.
However, in all previous stereoscopic systems, two stereoscopic images are generated from two separate optical systems. The images are then displayed separately to the left and right eyes of the surgeon or other observer, giving the perception of three dimensional imaging. The two separate images must be created with the same magnification, orientation, focus, and optical qualities. This presents a significant manufacturing problem due to tolerance, repeatability and assembly. The cost of such an instrument would be more than double the cost of a standard, two dimensional video imager, because two sets of optical lens assemblies, two cameras, and two electronic imagers, must be employed, and these must be matched and aligned to the maximum extent possible to display an acceptable stereoscopic pair of images on a video monitor. Moreover, because two separate camera systems are required, a three-dimensional imaging laparoscope or other endoscope or borescope would be significantly bulkier and heavier than a corresponding two-dimensional imaging instrument.
At the time being, full-color video borescopes and endoscopes are well known, and have been described, for example, in Danna et al. U.S. Pat. No. 4,491,365, Danna et al. U.S. Pat. No. 4,539,586, and Longacre et al. U.S. Pat. No. 4,523,224. The latter describes a color-sequential system in which sequential primary color light is supplied over a fiber optic bundle to illuminate a target area sequentially with primary color light.